1. Field of the Invention
The present invention relates to a method of deodorizing an ion-exchanged purified water for removing odor substances included in an ion-exchanged purified water obtained by treating new water by means of apparatuses for producing purified water of dual and mixed types.
2. Related Art Statement
In the fields of a semiconductor manufacturing and food production, it is necessary to use purified water obtained by treating water such as from a water service supply by means of an apparatus of producing purified water. Such apparatuses for producing purified water include a dual bed type and a mixed bed type are known. In the apparatus for producing purified water of the dual bed type, a treatment is performed in such a manner that now water is first passed through a strongly acidic cation exchange resin and then passed through a strongly basic anion exchange resin. In the apparatus for producing purified water of the mixed bed type, a treatment is performed in such a manner that now water is passed through a mixed layer of a strongly acidic cation exchange resin and a strongly basic anion exchange resin.
In the apparatuses for producing purified water, since use is made of ion-exchange resins, odor substances due to the ion-exchange resins may be sometimes included in the ion-exchanged purified water. In the field of semiconductor manufacturing and so on, there is no problem if the odor substances are included in the ion-exchanged purified water. However, in the field of food production and so on, if the odor substances are included in the ion-exchanged purified water, there arises such a problem that an odor is added to the produced food. In order to solve this problem, a method of deodorizing the ion-exchanged purified water by means of an activated carbon is disclosed in for example "Technic and management for treating a water by using an activated carbon," Nikkan Kogyo Sha (1978), page 130.
However, in the method of deodorizing the ion-exchanged purified water by means of an activated carbon mentioned above, there are following disadvantages (1).about.(3).
(1) Contamination of a treated water due to a salt component and an alkali component; PA1 (2) Contamination of a treated water due to microorganisms: PA1 (3) Frequent sterilizing treatments and regeneration treatments of activated carbon;
In the case of treating the ion-exchanged purified water by using an activated carbon, since impurities such as a salt component, an alkali component and so on are dissolved into the treated water from an activated carbon, the treated water is contaminated, so that the purity of the ion-exchanged purified water is decreased.
Since activated carbon has a porous structure and thus becomes a suitable medium for microorganisms, a large number of microorganisms are propagated in the activated carbon. Therefore, if the ion-exchanged purified water is treated by using activated carbon, these microorganisms are included in the treated water and the treated water is contaminated. In this manner, the treated water becomes unsanitary and thus it is not used for food production.
In order to regenerate an odor removing facility of the activated carbon and to sterilize the propagated microorganisms in the activated carbon, it is necessary to fire the activated carbon and to treat the activated carbon by using a high temperature steam. Moreover, the sterilizing treatment and the regenerative treatment of the activated carbon must be performed frequently.